The Siren Board

When and why did FS stop making the 2t?

theroofable wrote:When and why did FS stop making the 2t?

as has been said, the dissolution of Civil Defense removed the "need" for dual-tone sirens, and IIRC the 2T was like 98 dBC @ 100'. Really no need for it in this day and age.

I think FS still sells Modulators, DSAs,... UV controllers that run in dual tone mode stock and have read somewhere that some ASC electronic siren controllers have the ablilty to run in dual tone; don't quote me on that thogh.

Electronic "sirens" are just amplifier-speaker combinations. They can play whatever signal you feed them, within certain limits.

Jim Z wrote:

theroofable wrote:When and why did FS stop making the 2t?

as has been said, the dissolution of Civil Defense removed the "need" for dual-tone sirens, and IIRC the 2T was like 98 dBC @ 100'. Really no need for it in this day and age.

I said when as well.

Jim Z wrote:Electronic "sirens" are just amplifier-speaker combinations. They can play whatever signal you feed them, within certain limits.

I understand that. I was talking about buying a new UV powered siren from FS or an electronic siren from ASC, in which the controller is preset to be dual toned right out of the box, well factory or whatever. I know MCP and UltraVoice controllers are easy to program, but I don't know if ASC controllers are that way. I've never seen a current Whelen running as a dual tone siren, unless it has a UV controller driving it.

theroofable wrote:

Jim Z wrote:

theroofable wrote:When and why did FS stop making the 2t?

as has been said, the dissolution of Civil Defense removed the "need" for dual-tone sirens, and IIRC the 2T was like 98 dBC @ 100'. Really no need for it in this day and age.

I said when as well.

Late 1980s to early 1990s is my guess.

Along with Civil Defense no longer enforcing dual-tone sirens, dual-tone sirens are very inefficient. One row of ports gets more air than the other, and even the row getting more air gets less than a single tone rotor, because some of the air goes to the other row of ports. The ports are also smaller; they chop less air. I would assume they were harder to balance as well. Imagine balancing 12 forks on a wheel vs. 12 forks and 10 spoons, for lack of better example.

The above is only true on single rotor sirens. Dual rotor sirens have roughly double the output.

Hm... wouldn't having a siren put out two tones at once cause them to somewhat cancel each other over a long distance?

sirendude2012 wrote:Along with Civil Defense no longer enforcing dual-tone sirens, dual-tone sirens are very inefficient. One row of ports gets more air than the other, and even the row getting more air gets less than a single tone rotor, because some of the air goes to the other row of ports. The ports are also smaller; they chop less air. I would assume they were harder to balance as well. Imagine balancing 12 forks on a wheel vs. 12 forks and 10 spoons, for lack of better example.

Thunderbolt 1000T/1003s, while one side of the chopper does get more air, and Hurricanes are as loud as the blowers make them.

I don't know if that is true Daniel. The 2T22 and the STH-10 are both rated at 115db at 100 feet.

Brendan Ahern wrote:I don't know if that is true Daniel. The 2T22 and the STH-10 are both rated at 115db at 100 feet.

the STH-10 has a HUGE rotor compared to the xT22.